In the production of semiconductor devices, fine processing is performed by a lithography process. In the lithography process, such an issue is known that when a resist layer on a substrate is exposed to light using an ultraviolet laser such as a KrF excimer laser or an ArF excimer laser, due to the influence of a standing wave generated caused by the reflection of the ultraviolet laser on the surface of the substrate, a resist pattern having a desired shape cannot be formed. For solving the issue, it is adopted to provide a resist underlayer film (an anti-reflective coating) between the substrate and the resist layer. It is known that in a composition for forming the resist underlayer film, a novolac resin is used. For example, Patent Document 1 and Patent Document 2 describe a photoresist underlayer film forming material containing a resin having a repeating unit formed by converting a compound having a bisphenol group into novolac. Further, Patent Document 3 describes a composition for an anti-reflective coating that contains a polymer having in the backbone of the polymer, an aromatic ring in which three or more rings are fused and can be spin-coated. However, in Patent Documents 1 to 3, there is neither disclosed nor suggested a resist underlayer film forming composition containing a polymer having the fused aromatic ring in a side chain thereof.
There is also known a lithography process in which due to the thinning of the resist layer that is required according to the miniaturization of a resist pattern, at least two layers of resist underlayer film are formed and these resist underlayer films are used as a mask material. Examples of the material for forming the at least two layers include organic resins (for example, an acrylic resin and a novolac resin), silicone resins (for example, an organopolysiloxane), and inorganic silicon compounds (for example, SiON and SiO2). When the dry etching is performed using as a mask, a pattern formed from the organic resin layer, the pattern is necessary to have etching resistance against an etching gas (for example, a fluorocarbon). As a composition for forming such an organic resin layer, for example, Patent Document 4 discloses a composition containing a polymer containing a heterocyclic aromatic moiety.